In 1876, New York artist sculpted Cleopatra's death; 100 years later, the lost artwork was discovered while being used as a horse's gravestone

• Many of history's most beloved works still remain lost to time.
• From books to sculptures and even paintings, all works of art that were adored in their day are now either destroyed or impossible to find.
• For instance, Sophocles was known to have written over 120 plays; only 7 are known to survive to this day.